I have no experience with Fineco, and for what I read here I will never have.
However I do have a bad experience with Plus500.
I have traded with Oil CFD for 6 months. I do not recall any dodgy behaviour of Plus500 platform. It is just annoying when you cannot place a pending order when the market is within the spread range.
Last month I gave a try with Oil Options of Plus500.
My only guilt is I didn't study deep enough  before stepping into this field.
First of all, and maybe most of all, Plus500 Oil Options, are not Options, they are Options CFD, therefore once they expire, you cannot exercise the option itself, which is quite a big issue.
Then there are other differences between Options and Options CFD, of course all those differences make Option CFD a crap.
The big problem is that Plus500 says to provide "Oil Options", which is not true: they provide Oil Option CFDs.
Option CFDs, like any other CFD, allow Traders to speculate on underlying assets' value without actually owning the asset itself. In few words, an Option CFD mirrors the relative Option, namely it just copies the underlying asset value.
The difference between owning an Option or owning its relative Option CFD, is like the difference between owning a Ferrari or owning a mirror in front of Ferrari: you see the same Ferrari but you cannot go to highway driving a mirror.
The Crude Oil made a bottom a few hours earlier, I and my trading mates figured out that it was going to retest that bottom. I was trading with Option CFDs. I had Oil Put45.5, my strategy was to close it and reverse with a Call48 in that minimum. When the Crude Oil retested that minimum, both Put45.5 and Call48 were disabled, "greyed", so I could not do any operation with them.
I complained with Plus500 and, once escalated the case, I was told the following: "When there is low demand for a certain instrument in the real market, fewer transactions are made, and therefore we may not receive price quotes from our providers during such times. Therefore it is possible that regardless of its stated trading hours, the instrument may appear as unavailable for trading."
That may be true for a real asset like Options, definitively that is not true for Option CFD.
A Trader on Option CFDs speculates on underlying Option's value; if the platform disables the instrument that makes the speculation possible, and if that happens in a convenient moment for the platform, the Trader has all rights to claim for scam.
As an Option CFD holds the underlying Option value until it is updated with the next value, the same should happen when the Option is having fewer transactions.
While the Option is having fewer transactions, the Plus500 platform could at least accept pending orders for the relative Option CFD, but it doesn't.
The value of any asset with fewer transactions will not change till the next transaction happens, therefore there is no point in disabling that Option CFD during those intervals, there is no point in making unavailable a value spaculating instrument during those intervals because an Option CFD is not an Option.
Beware, stay away from Plus500 Oil Options.